Autopilot system controlling entry of a craft into forbidden zones

ABSTRACT

In combination with the autopilot system of an aircraft an onboard control system inaccessible to the pilot responds to ground transmitted or onboard computed geographical position signals to restrict pilot heading or descent maneuvers when the aircraft enters a forbidden geographical zone.

United States Patent 1191 Williams Y 14 1 July 31, 1973 1 AUTOPILOTSYSTEM CONTROLLING 3,414,214 12/1968 Robinsonet al 244/15 A ENTRY OF ACRAFT INTO FORBIDDEN 3,434,l4l 3/1969 Welti 343/ l 12 CA X ZONES3,623,090 ll/l97l Gilbert et al.. 343/112 CA X g 3,644,722 2/1972 Hobbset al 244/77 D X [76] Inventor: Thurston Y. Williams, c/o The O. K.2,952, 9/1960 Guarino Tool Co., lnc., Milford, NH. 03055 3,015,4581/1962 Marx v 2,985,4l0 5/1961 Richter et al. 244/77 V [2 1 Flledr 19702,953,329 9/1960 Ciscel 244/77 v [211 pp. No 83 271 2,322,225 6/1943Crane et al.... 244/77 B a Primary Examiner-Milton Buchler [52] 11.8.CI...... 244/77 B, 235/l50.22, TBS/150.27, Assistant gmminer stphen 3Kunin 244/771) 318/584 Attorney-James H. Grover [51] Int. Cl. 1364c13/18 1 [58] Field ofSearch 244/77 B, 77 V, 77 D,

244/155, 5 A, 5.14, 3.19; 73/178 R T; [57] 1 ABSTRACT 235/1502. 5 2,150.26, 150.27; 318/581, In combination with the autopilot system of anaircraft 583, 584; 343/ 107,- 108 R, 112 R, 112A, 1 12 an onboardcontrol system inaccessible to the pilot rer 4 "1 CA sponds to groundtransmitted or onboard computed i geographical position signals torestrict pilot heading or [56] R f r n Cit d descent maneuvers when theaircraft enters a forbidden UNITED STATES PATENTS P 3,088,697 6/1963 2Claims, 3 Drawing Figures Cutler 244/15 A CONVENTIONAL AUTO PILOT PlTCHRATE L0 01 g PILOT} '2 PITCH PAIENIEDJULBI ma PITCH PI LOT CONTROLCONVENTIONAL AUTO PILOT P-ITCH RATE LOOP,

PRESET CLIMB ANGLE 26 RELAY AND PITCH- RATE IGNAL 4 jig/I. IL

PILOT- INACCESSIBLE DRIVE E LEV.

E LE VATOR PITC H RATE SENSOR THR ESHOLD GATE DETECTOR ALTIMETERCOMPUTER a PRESET CODE COINCID.

GATE

GEOG

POSITIO REGISTER AI R SPEED METER GROUND SIGNAL POSITION COMPUT ER ALTI-METER MECH. DRIVE PILOT I HEAD] CONTROL PILOT- INACCESSIBLE PRESETHEADING HE ADIN G LOOP PILOT- INACCESSIBLE F'- DESCENT IGI M ANUALCONTROL EL EVATOR TCLIMB MECHAN ICAL DESCENT 3 TOP RUDDER COMPUTPOSITION FIG?) INVENTORI THURSTO V. W LIAMS W ATTVS AUTOIILOT SYSTEMCONTROLLING ENTRY OF A CRAFT INTO FORBIDDEN ZONES Existing autopilotsystems permit the pilot of various craft and vehicles manually to setthe heading, and in aircraft the roll and pitch of the-craft, andtemporarily to turn over such preset maneuvers to the control of onboardautomatic systems. The pilot also has available onboard an automaticaltimeter, air speed meter and a computer for calculating andregistering for display the geographical position of the craft withrespect to its departure point. It is also possible with loran or otherradio navigation beacons to supply position information to the craftfrom the ground.

It is the object of this invention to use such existing onboardequipment in 'a' system, inaccessible to and therefore beyond thecontrol of the pilot, for restricting,to a'degree compatible with thesafety of the craft, the entry or descent of the craft intoanundesirable or prohibited geographical zone.

According to one form of the invention a craft control systemcomprisesmeans for maneuvering the craft, pilot-inaccessible means forregistering the entry of the craftinto a predetermined geographicalzone, and pilot-inaccessible means responsiveto the position register toprevent a selected maneuver of the craft in the predeterminedgeographicalzone. The prevented maneuver may be a turn toward aprohibited zone, continuance on a course into such a zone, or, in theease of aircraft, descent below a "predetermined altitude.

Further aecordingto-the invention an aircraft control "system comprisesmeans for adjusting the climb, de-

scent and heading of the aircraft, means for sensing desce'ntof theaircraft "below a predetermined altitude, meansto registera geographicalposition of the aircraft and'producea'control signal when .apredetermined position is registered, and means responsive to thealtitude sensing me ansand position registering means to prevent theaircraft adjusting means from causing descent of the aircraftbelow thepredeterminedaltitude.

' -ln"-the accompanying drawing FIG. 1 shows an electronic elevatorcontrol system; -:FIG. 2 shows schematically a mechanicalaircraftelevator control-system; and. i

"FIG. 3 showsan electronicheading control system. I

" Asshown in-FIG. l the'elevator-l of an aircraft is normally.adju'stedbya 'pilotcontrol Ztoset'the pitch of the aircraft'forclimbor descent.In a conventional pitch rate electro-mechanical loop 3 the pilot'smanual setting is transmitted electricallyto a pitch rate-signalgenerator 4 which energizes the drive-6 for the elevator.'.Asensor'7,ofthe elevator'pitch transmits theactual elevator pitch in a:loop back to the generator 4 for comparison and-correctionofjthe pitchrate'to the pilots setting. The aircraft=willassume and continue on theangle-of climbor descent untilthe pilot changes the pitch 'setting. i v

Conventional onboard aircraft equipment also includcsa computer8.receiving'electrical heading signals from a free directional. gyro9and velocity signals from an air speed meter :lzLFrom these signals thegeographical position iiscontinuously calculated by the computer-and theinstantaneous latitude and longitude is coded for temporarystoragein'the memory elements, for example A,B-,C,D,fE. of thecomputer's register 12. The registered position code ispresented onlatitude and longitude displays 13 and 14. In FIG. I a presclectedcombination of register elements A,C and D are connected to coincidencegate 15 or equivalent logic device which produces a control signal whenany one of a number of geographical positions are registered by latitudeand longitude in the computer. It will be understood that while fiveregister elements, A to E, are 'shown as a simplified example, a muchlarger number will actually be used to enable registering in codevarious positions. Any group of coded positions may be selected whichrepresent a geographical zone tens or hundreds of miles in area. Thememoryelements, or combination thereof, representing all positions inthe a zone may be connected by switches or gate elements 16 ing flightif aircraft enters the preselected zone the computer will register aposition in the zone in a combination of register elements connected tothe coincidence gate 15, causing the gate to pass a control signal to anAND gate 18. Register of positions outside'the zone will not coincidewith the preselected connection through switches 16 and will not affectthe coincidence gate 15. v

To pass the control signal from the computer the AND gate 18 must alsoreceive apreselected altidude signal. Conventional onboard altimeter l9continuously measures the aircrafts altitude in flight for normalpresentation on a display 21. The measurement by the altimeter 19 isalso sensed by a threshold detector 22 which produces a secondarycontrol signal when the aircraft descends below a preselected height,say 5000 feet, set in the threshold detector prior to take-off andinaccessible to the pilot thereafter.

When the computer registers a position in the preselected geographicalzone, and the altimeter registers a positionbelow the preselectedaltitude, the AND gate 18 will pass the control signal to switchingmeans such as a relay 23, transferring contacts 24 and 26-from theposition shown in FIG. 1. The pilot operated pitch control 2 isdisconnected by contact 24 from the pitch rate loop 3, at least to theextent of controlling descent pitch, and a substitute preset pitchsignal source 27 is eonnected to the pitch rate loop by contact 26 Thepreset signal source 27 preferably corresponds to a slow climb signalfrom the pilot control and, beyond It is also possible to supply thegeographical position information to the computer 8 through an onboardreceiver of ground signals 25 as shown by the broken line arrow. Theground signal receiver is inaccessible to the air crew as are allcomponents of the-system of FIG. 1 located in the lower broken lineportion of FIG. I.

In FIG. 2 an alternative pitch rate control is shown in a pilot systemhaving a manual control 31 for the aircraft elevator I. A mechanicalstop 32 is movable by a mechanical drive 33 to a position 32 in which itcan adjust the elevator 1. from a descent pitch position, if it is indescent pitch, and hold the elevator 1 in a slight climb pitch,overriding the manual or other elevator control 31. The mechanical drive33 performs the function of the AND gate 18 and the threshold detector22 in responding to signals from the position computer 8 and altimeter19 of, or alternatively to the ground signal receiver 25, of FIG. 1, andprevents descent of the aircraft below a predetermined altitude while ina preselected zone.

Either of the above systems allow unlimited pilot control outside thepreselected geographical zone and inside the zone above the preselectedaltitude. In the zone and below the preselected altitude the pilot is allowed all maneuvers except pitching for descent below that altitude.

As an alternative or in combination with the pitch control systemsdescribed above a heading control system is shown in FIG. 3. Aconventional autopilot heading loop 41 for controlling a rudder 42 ofair or surface craft is substantially the same as the described pitchrate loop, and normally receives heading signals from a pilot headingcontrol 43, the only component of the system accessible to the pilot,or, of course, to the crew or passengers. Arrival, approach or othermaneuver of the craft into a preselected geographical zone is registeredin the position computer 8 as in FIG. 1, causing the relay 23 totransfer its contacts 24 and 26. Contact 24 then disconnects the pilotheading control 43 and connects a ground preset heading signal source 44to the heading loop 41. The heading signal source 44 may be preset for aspecific heading or for a specific heading change, for example a 180turn which will adjust the rudder 42 to head the craft out of thepreselected zone. The aircraft is thus prevented from entering theselected zone to anysubstantial degree. Since both heading and pitchcontrol systems are available on aircraft,

both may be connected with the same onboard com- .puter in theway shownin FIGS. ,1 and It should be understood that the present disclosure isfor the purpose of illustration only and that this invention includesall modifications andequivalents which fall within the scope of theappended claims. I claim:

1. A pilotted aircraft control system comprising:

means for maneuvering the craft,

means beyond the control of the pilot to register continuously, theentry of the craft into and continued presence in a predeterminedgeographical zone, and means beyond the control of the pilot responsiveto said register and controlling said maneuvering means to prevent aselected maneuver of the craft in said geographical zone, the registermeans being operative to control the maneuvering. means so long aspresence in the zone is registered,

wherein said maneuvering means comprises an elevator or like aircraftpitch element, characterized by altitude sensing means connected to saidresponsive means to cause said responsive means to control the pitchelement so as to prevent descent of the aircraft below a predeterminedaltitude in said geographical zone.

2. A pilotted aircraft control system comprising means for adjustingclimb and descent of the aircraft,

means for sensing descent-of the aircraft below a predeterminedaltitute, means beyond the control of the pilot to register thegeographical position of the aircraft and continuously produce a controlsignal when a predetermined position is registered, and

means beyond pilot control responsive to the sensing means and registermeans and controlling the climb and descent adjusting means only toprevent said adjusting means from causing descent of the aircraft belowsaid predetermined altitude when the aircraft is in said geographicalposition.

1. A pilotted aircraft control system comprising: means for maneuveringthe craft, means beyond the control of the pilot to registercontinuously the entry of the craft into and continued presence in apredetermined geographical zone, and means beyond the control of thepilot responsive to said register and controlling said maneuvering meansto prevent a selected maneuver of the craft in said geographical zone,the register means being operative to control the maneuvering means solong as presence in the zone is registered, wherein said maneuveringmeans comprises an elevator or like aircraft pitch element,characterized by altitude sensing means connected to said responsivemeans to cause said responsive means to control the pitch element so asto prevent descent of the aircraft below a predetermined altitude insaid geographical zone.
 2. A pilotted aircraft control system comprisingmeans for adjusting climb and descent of the aircraft, means for sensingdescent of the aircraft below a predetermined altitute, means beyond thecontrol of the pilot to register the geographical position of theaircraft and continuously produce a control signal when a predeterminedposition is registered, and means beyond pilot control responsive to thesensing means and register means and controlling the climb and descentadjusting means only to prevent said adjusting means from causingdescent of the aircraft below said predetermined altitude when theaircraft is in said geographical position.